scholarly journals Bacterial synthesis of PbS nanocrystallites in one-step with l-cysteine serving as both sulfur source and capping ligand

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shiping Wei ◽  
Ce Guo ◽  
Lijuan Wang ◽  
Jiangfeng Xu ◽  
Hailiang Dong
Keyword(s):  
Surface Characterization ◽  
Blue Shift ◽  
Band Gap Energy ◽  
Sulfur Source ◽  
Lysinibacillus Sphaericus ◽  
Quantum Size ◽  
Naturally Occurring ◽  
Vis Spectroscopy ◽  
One Step

AbstractThe green bacterial biosynthesis of lead sulfide nanocrystallites by l-cysteine-desulfurizing bacterium Lysinibacillus sphaericus SH72 was demonstrated in this work. Nanocrystals formed by this bacterial method were characterized using the mineralogical and morphological approaches. The results revealed that the microbially synthesized PbS nanocrystals assume a cubic structure, and are often aggregated as spheroids of about 105 nm in size. These spheroids are composed of numerous nanoparticles with diameter 5–10 nm. Surface characterization of the bacterial nanoparticles with FTIR spectroscopy shows that the l-cysteine coats the surface of PbS nanoparticle as a stabilizing ligand. The optical features of the PbS nanocrystallites were assessed by UV–Vis spectroscopy and PL spectroscopy. The maximum absorption wavelength of the bacterial PbS particles occurs at 240 nm, and the photoluminescence emission band ranges from 375 to 550 nm. The band gap energy is calculated to be 4.36 eV, compared to 0.41 eV for the naturally occurring bulk PbS, with this clear blue shift attributable to the quantum size effect.

scholarly journals Exploiting the Amazing Diversity of Natural Source-Derived Polysaccharides: Modern Procedures of Isolation, Engineering, and Optimization of Antiviral Activities

Polymers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 136
Author(s):  
Bimalendu Ray ◽  
Martin Schütz ◽  
Shuvam Mukherjee ◽  
Subrata Jana ◽  
Sayani Ray ◽  
...  
Keyword(s):  
Structural Characteristics ◽  
Antiviral Drug ◽  
Natural Source ◽  
Target Interaction ◽  
Charge Densities ◽  
Linkage Pattern ◽  
Naturally Occurring ◽  
Antiviral Activities ◽  
One Step

Naturally occurring polysaccharide sulfates are highly diverse, owning variations in the backbone structure, linkage pattern and stereochemistry, branching diversity, sulfate content and positions of sulfate group(s). These structural characteristics bring about diverse sulfated polymers with dissimilar negative charge densities and structure–activity relationships. Herein, we start with a short discussion of techniques needed for extraction, purification, chemical sulfation, and structural characterization of polysaccharides. Processes of isolation and sulfation of plant-derived polysaccharides are challenging and usually involve two steps. In this context, we describe an integrated extraction-sulfation procedure that produces polysaccharide sulfates from natural products in one step, thereby generating additional pharmacological activities. Finally, we provide examples of the spectrum of natural source-derived polysaccharides possessing specific features of bioactivity, in particular focusing on current aspects of antiviral drug development and drug–target interaction. Thus, the review presents a detailed view on chemically engineered polysaccharides, especially sulfated derivatives, and underlines their promising biomedical perspectives.

Effect of vacuum annealing on the properties of one step thermally evaporated Sb2S3 thin films for photovoltaic applications

2021 ◽  
Author(s):  
Emna Gnenna ◽  
Naoufel Khemiri ◽  
Minghua Kong ◽  
Maria Isabel Alonso ◽  
Mounir Kanzari
Keyword(s):  
Thin Films ◽  
Annealing Temperature ◽  
Vacuum Annealing ◽  
Xrd Analysis ◽  
Band Gap Energy ◽  
Chemical Compositions ◽  
Optical Parameters ◽  
X Ray ◽  
Vis Spectroscopy ◽  
One Step

Sb2S3 powder was successfully synthesized by solid state reaction technique using high-purity elemental antimony and sulfur. Sb2S3 thin films were deposited on unheated glass substrates by one step thermal evaporation and annealed under vacuum atmosphere for 2 hours at different temperatures 150, 200 and 250 °C. Different characterization techniques were used to better understand the behavior of the Sb2S3 material. X-ray diffraction (XRD) and Raman spectroscopy confirmed the formation of pure Sb2S3 powder with lattice parameters a = 11.07 Å, b = 11.08 Å and c = 3.81 Å. The effect of vacuum annealing temperature on the properties of the films was studied. XRD analysis revealed that as-deposited and annealed films at 150ºC were amorphous in nature whereas those annealed at T ≥ 200°C were polycrystalline with a preferred orientation along (201) plane. The crystallite size of the polycrystalline films showed a decrease from 75.8 to 62.9 nm with the increase of the annealing temperature from 200 to 250 °C. The Raman analysis showed several peaks corresponding to the stibnite Sb2S3 phase. The surface morphology of the films was examined by atomic force microscopy (AFM). The surface roughness decreases slightly as the transformation from the amorphous to the crystalline phase occurs. The chemical compositions of Sb2S3 films were analyzed by energy dispersive X-ray spectroscopy (EDS), revealing that all films were Sb-rich. The optical parameters were estimated from the transmittance and reflectance spectra recorded by UV-Vis spectroscopy. A reduction in the direct band gap energy from 2.12 to 1.70 eV with the increase of annealing temperature was also found.

A Simple Method for Synthesis of PbS Nanoparticles Using 2-Mercaptoethanol as the Capping Agent

2012 ◽  
Vol 31 (6) ◽  
pp. 723-725 ◽  
Author(s):  
Gholamreza Nabiyouni ◽  
Parviz Boroojerdian ◽  
Kambiz Hedayati ◽  
Davood Ghanbari
Keyword(s):  
Electron Microscopy ◽  
Electronic Absorption Spectra ◽  
Blue Shift ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Sulfur Source ◽  
Capping Agent ◽  
X Ray Diffraction ◽  
Simple Method ◽  
Vis Spectroscopy

AbstractLead sulfide nanoparticles were synthesized at room temperature via a simple chemical reaction. In this synthesis, 2-mercaptoethanolwas used as the capping agent and sodium sulfide was used as a sulfur source. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet-visible (UV-vis) spectroscopy and Fourier transform infrared (FT-IR) spectroscopy Electron microscopy study showed that without using a capping agent the bulk PbS is obtained, while adding the mercaptoethanol leads to production of nanoparticles. We found that the electronic absorption spectra as well as the particle sizes depend on the used capping agents. Two exitonic peaks with a large blue shift were observed when mercaptoethanol was used.

scholarly journals Synthesis and Characterization of Aluminum Doped Zinc Oxide Nanostructures via Hydrothermal Route

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
A. Alkahlout ◽  
N. Al Dahoudi ◽  
I. Grobelsek ◽  
M. Jilavi ◽  
P. W. de Oliveira
Keyword(s):  
Zinc Oxide ◽  
Blue Shift ◽  
Zinc Oxide Nanostructures ◽  
Hydrothermal Route ◽  
Molar Ratios ◽  
Oxide Nanostructures ◽  
Nitrate Precursor ◽  
Vis Spectroscopy ◽  
Aluminum Doped Zinc Oxide

Stable crystalline aluminum doped zinc oxide (AZO) nanopowders were synthesized using hydrothermal treatment processing. Three different aluminum precursors have been used. The Al-precursors were found to affect the morphology of the obtained nanopowders. AZO nanoparticles based on zinc acetate and aluminum nitrate have been prepared with different Al/Zn molar ratios. XRD investigations revealed that all the obtained powders have single phase zincite structure with purity of about 99%. The effect of aluminum doping ratio in AZO nanoparticles (based on Al-nitrate precursor) on structure, phase composition, and particle size has been investigated. The incorporation of Al in ZnO was confirmed by UV-Vis spectroscopy revealing a blue shift due to Burstein-Moss effect.

Characterization of MnS Thin Films Deposited by Chemical Bath Deposition

2019 ◽  
Vol 969 ◽  
pp. 433-438 ◽  
Author(s):  
Dattatraya K. Sonavane ◽  
S.K. Jare ◽  
M.A. Shaikh ◽  
R.V. Kathare ◽  
R.N. Bulakhe
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Band Gap ◽  
Chemical Bath Deposition ◽  
Band Gap Energy ◽  
Sulfur Source ◽  
X Ray Diffraction ◽  
Glass Substrates ◽  
Double Beam

Glass substrates are used to deposit thin films utilizing basic and value effective chemical bath deposition (CBD) technique. The films were prepared from the mixture as solutions of manganous acetate tetrahydrate [C4H6MnO44H2O] as a manganese source, thiourea [(H2 N) 2 CS] as a sulfur source and triethanolamine (TEA) [(HOC2H4)3N] as a complexing agent.In the present paper the deposition was successfully done at 60 °C temperature. The absorption properties and band gap energy were determined employing double beam spectrophotometer. The optical band gap value calculated from absorption spectra of MnS thin film is found to be about 3.1eV.The MnS thin film was structurally characterized by X-ray Diffraction (XRD). The MnS thin film was morphologically characterized by Scanning Electron Microscopy (SEM) and elemental analysis was performed using EDS to confirm the formation of MnS.

Preparation and characterization of silver nanoparticle-porphyrazine composites

2013 ◽  
Vol 17 (10) ◽  
pp. 928-933
Author(s):  
Altuğ Mert Sevim ◽  
Ayşe Selda Keskin ◽  
Ahmet Gül
Keyword(s):  
Silver Nanoparticles ◽  
Chemical Reduction ◽  
Reduction Process ◽  
Silver Ions ◽  
Organic Medium ◽  
Nano Particles ◽  
Effective Manner ◽  
Vis Spectroscopy ◽  
One Step

A one step chemical reduction process was used for the preparation of hydrophilic silver nanoparticles ( AgNP ) using silver nitrate, sodiumborohydride and polyvinylpyrolidone as stabilizer. In the case of hydrophobic silver nanoparticles reduced silver ions were stabilized with cetyl trimethylammonium bromide (CTAB). The resultant nano particles were characterized by absoption spectra and their interactions with cationic cobalt (QCoPz) and neutral magnesium (MgPz) porphyrazines in water and in organic medium were investigated by using UV-vis spectroscopy and zeta potential techniques. It is confirmed that both metalloporphyrazine molecules interact with silver nanoparticles in an effective manner. The possible arrangement of the porphyrazines on the surfaces of the hydrophilic and hydrophobic AgNPs has been also discussed according to obtained spectroscopic results. These well-characterized novel AgNP -metalloporphyrazine composites are expected to be useful in optical and catalytic applications.

Near Surface Characterization of an Impinging Elliptic Jet Array

1999 ◽  
Vol 121 (2) ◽  
pp. 384-390 ◽  
Author(s):  
Simona C. Arjocu ◽  
James A. Liburdy
Keyword(s):  
Surface Characterization ◽  
Large Scale ◽  
Near Surface ◽  
Large Scale Structures ◽  
Aspect Ratios ◽  
Naturally Occurring ◽  
Turbulence Velocity ◽  
Axis Switching ◽  
Jet Array

In this study naturally occurring large-scale structures and some turbulence characteristics within an impinging jet array are investigated. The dynamics of a three-by-three elliptic jet array are analyzed relative to the flow structures within the array. With applications to electronic component cooling, low Reynolds number conditions, Re = 300 to 1500, are presented. Two jet aspect ratios are used, 2 and 3, with identical jet hydraulic diameters and jet-to-jet space. The effects of impinging distance are studied in the range of one to six jet hydraulic diameters. Flow visualization and PIV are used for the identification of structures and quantitative analysis. These results are used to evaluate the integrated surface layer vorticity, Γ*, which is shown to depend on the jet aspect ratio and impingement distance. Also, a transport coefficient is presented, based on a turbulence velocity and length scales. This coefficient is shown to experience a maximum value versus impingement distance that coincides with the location of axis switching.

scholarly journals Synthesis and Characterization of Copper Sulphide Nanoparticles in Aqueous Surfactant Solutions

1998 ◽  
Vol 16 (8) ◽  
pp. 667-677 ◽  
Author(s):  
Santosh K. Haram ◽  
Anand R. Mahadeshwar ◽  
Sharad G. Dixit
Keyword(s):  
Blue Shift ◽  
Copper Sulphide ◽  
X Ray ◽  
Surfactant Solutions ◽  
Transmission Electron ◽  
Ammonia Complex ◽  
Vis Spectroscopy ◽  
The Stability ◽  
Aqueous Micellar Solutions

Copper sulphide nanoparticles were synthesized by reacting a copper-ammonia complex with thiourea in aqueous micellar solutions of cationic, non-ionic and anionic surfactants. A blue shift in the absorption spectra revealed the formation of size-quantized nanoparticles. The influence of micelles in mediating the stabilization was studied by carrying out the reactions in surfactant solutions above and below the critical micelle concentration. The effect of thiourea on the stability of the nanoparticles was studied by synthesizing the nanoparticles at different mole ratios of reactants. Characterization of the nanoparticles was achieved by the use of transmission electron microscopy (TEM), X-ray powder diffraction (XRD), energy dispersive X-ray microanalysis (EDAX) and UV–vis spectroscopy.

Improved Photoelectrode of Dye-Sensitized Solar Cell Using a ZnO/Zn2TiO4

2011 ◽  
Vol 695 ◽  
pp. 505-508 ◽  
Author(s):  
Warut Koonnasoot ◽  
Atcharawan Gardchareon ◽  
Supab Choopun ◽  
Duangmanee Wongratanaphisan
Keyword(s):  
Solar Cell ◽  
Band Gap Energy ◽  
Dye Sensitized Solar Cell ◽  
X Ray Diffraction ◽  
Zinc Titanate ◽  
Gap Energy ◽  
Dye Sensitized ◽  
Vis Spectroscopy ◽  
Titanate Nanostructures

Zinc titanate nanostructures were prepared by oxidation reaction technique. Here Zn mixed with 0, 10, 20 and 30 mol% of TiO2powder was screened on alumina and FTO substrate, and then sintered at 400–600°C for 12 h under normal atmosphere. Through a detailed field emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), and x-ray diffraction (XRD) indicated that the nanostructures exhibited belt-like shapes of Zn2TiO4phase. Moreover, the belt-like nanostructures of the synthesized Zn2TiO4were studied in terms of optical properties by the UV-vis spectroscopy (UV-vis) to obtain band gap energy (Eg). The results showed that the Eggap energy ranged from 3.57 eV to 3.63 eV as the mol% of TiO2increased. In addition to the characterization of the nanobelts, the synthesized Zn2TiO4 nanostructures were applied as a bilayer semiconductor electrode in ZnO-based dye-sensitized solar cell (DSSC). It was shown that the use of Zn2TiO4nanostructure with 10 mol% TiO2in the ZnO/Zn2TiO4electrode components of the DSSC revealed the highest obtainable efficiency.

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